So, how about that aircraft carrier-sized asteroid that buzzed the earth earlier this week--crazy right? Zipping through the cosmos at approximately 30,000 miles per hour and measuring roughly 1000 feet long, Asteroid 2005 YU55 definitely could have ruined a lot of people’s days if it’d passed 202,000 miles closer--a pittance of a distance by astronomical standards--to us than it did. Are there other space bound rocks out there hellbent on our planet’s destruction? You betcha. Do we know when or how likely it is for them to strike? Nope, but the vigilant space geeks over at Near-Earth Asteroid Tracking do, and their online presence is our Cool Site of the Week.